Green’s Dictionary of Slang

gylrig n.

[Polari; ? backslang of SE girl or girly]
(UK gay)

1. a desirable person.

[UK]K. Williams Diaries 18 June 133: Walked to the park where there was a fabulous gylrig but not available I fancy.

2. sexual activity.

[UK]K. Williams Diaries 20 June 133: Popped into the news theatre in Piccadilly! — phew! the gylrig going on!